docs: def get_success_url(self):
          """ Returns the URL to redirect the user to upon valid form processing. """
          messages.success(self.request, self.success_message)
  
          if self.object.is_topic_head and self.object.is_topic_tail:
              return reverse(
                  'forum:forum',
                  kwargs={
                      'slug': self.object.topic.forum.slug, 'pk': self.object.topic.forum.pk,
                  },
              )
  
          return reverse(
              'forum_conversation:topic',
              kwargs={
                  'forum_slug': self.object.topic.forum.slug,
                  'forum_pk': self.object.topic.forum.pk,
                  'slug': self.object.topic.slug,
                  'pk': self.object.topic.pk,
              },
          )